EEVblog #705 - Mailbag

[EEVblog]

Mailbag Monday
This week two very notable people send in mailbag items!

SPOILERS:
Book Review: Iconic: A Photographic Tribute to Apple Innovation: http://amzn.to/1sVc5Ii

Colin Mitchell from Talking Electronics:
http://www.talkingelectronics.com/
555 Timer LED scanner kit:
http://www.talkingelectronics.com/projects/50%20-%20555%20Circuits/50%20-%20555%20Circuits.html
List of magazines for download:
Basic Electronics Course: http://www.talkingelectronics.com/projects/BasicElectronics-1A/BasicElectronics-1A_Page1.html
Interviews with Colin Mitchell: https://www.youtube.com/playlist?list=PL7359E3DC6FF7FA43

Bil Herd: http://www.herdware.com/
Designer of the Commodore C128 among others.
Amp Hour show with Bil: http://www.theamphour.com/222-an-interview-with-bil-herd-zany-z80-zygology/

Joystick Porn from: http://www.controldevices.net/

Hazet Screwdrivers: http://www.hazet.de/produktkatalog/index.php?language=en&cPath=2230

An old Russian DIY Sinclair clone home computer: http://www.arcadebox.ru/

Stay Adhesive: http://www.stayadhesive.com/

Weston Model 310 AC/DC Wattmeter from 1944!

[Fungus]

Re. the proportional joystick movement: Are you sure there's no Hall effect sensors in there? Those fixed output points (the ones with with wipers) could be for calibration of the Hall effect sensors.

PS: Love that Spectrum clone!

And yeah, what's the deal with security cameras? Why does all "security camera footage" look like it was recorded on a 1990s mobile phone?

[necessaryevil]

I'm a little worried my mail never arrived...
An old calculator and a pcb for a mosfet rectifier....

[boobo-oobo]

Hello.

I'm a long time follower of EEVblog on YT, but just registered today on the forum cause Im interested in the CCD cameras segment, I need some older CCD cameras for a project Im doing but i cant find them around where I live. I wonder if anyone knows how can i contact Matt Nelson, or if anyone of the viewers has any idea where to get these older cameras still available for purchase?

Thanks.

[PeterL]

Nice to see Sagan's Engineering mindset. He instantly recognizes the Lego, but he only mention's the boat after daddy does.
Good for you Sagan: it's Lego, it can be anything. Don't limit yourself to a picture on the box!

[ultranalog]

On that video camera board, next to the transistor, the silkscreen seems to read 'FADE IN', so I suppose it is a clamp but you can externally supply a control signal to fade the video in and out.

[CrashO]

I'm a little worried my mail never arrived...
An old calculator and a pcb for a mosfet rectifier....

When did you ship it? > 3 months is no exception on the mailbag 

[max_torque]

Re. the proportional joystick movement: Are you sure there's no Hall effect sensors in there? Those fixed output points (the ones with with wipers) could be for calibration of the Hall effect sensors.

PS: Love that Spectrum clone!

And yeah, what's the deal with security cameras? Why does all "security camera footage" look like it was recorded on a 1990s mobile phone?

Could also use carbon track resistor elements directly on the pcb?  Probably "dualled" up for redundancy/safety also.  I'd imagine these days, most system integrators will be choosing a J-stick with a CAN or similar serial network output to allow complex diagnosis / failure modes to be supported.   Really high reliability positional measurement in nasty environments tends to move to non-contact methods, often with resolvers or other similar "active" sensing elements!

I'd love to see the Joystick that moves the ISS Canadarm for example, as you can bet that is multiple redundant etc ;-)

http://en.wikipedia.org/wiki/Canadarm

[Yago]

Nice to see Sagan's Engineering mindset. He instantly recognizes the Lego, but he only mention's the boat after daddy does.
Good for you Sagan: it's Lego, it can be anything. Don't limit yourself to a picture on the box!

You could see Sagans' 3d spatio-reasoning developing a couple of vids back.
Dave did the thumbs up and this time Sagan realised the differing perspectives from being a signaller from a viewer.

The Joystick chap posted in the comments section further information regarding the use of a carbon track AS WELL as the switching on that particular unit.

[Fungus]

Re. the proportional joystick movement: Are you sure there's no Hall effect sensors in there? Those fixed output points (the ones with with wipers) could be for calibration of the Hall effect sensors.

Could also use carbon track resistor elements directly on the pcb?

Sure.... It just seems weird that they would require custom-made Hall effect switches for the green buttons on top (ordinary microswitches weren't reliable enough!) but then use carbon tracks and wipers for the joystick's position sensing. I'd expect some sort of non-mechanical sensors in there.

[coppice]

What are the terminals on that power meter made from? They don't look like the usual plated brass. They look kinda brushed stainless steel, but that's not a good conductor, and was a rare material in 1944.

[G7PSK]

The watt meters terminals are quite likely to be inconel or a similar alloy or chrome or nickel plated brass , the four smaller one's with the straps would be range selection, shorting out or bypassing the shunt resistors and or putting them into series. The actual shunt windings will be within the metal can.I have had pieces of test equipment from the Cambridge university labs that looked like they were never used, some dating back to the 1920's, nothing recently though as the auctioneer who ran the sales for them died some years back.

[allikat]

I'd love a video showcasing some of the ancient stuff Dave has been sent, like that watt meter, in action if possible.  Going in to why these instruments existed, what they do and why you'd use one (back in the day).  Would make a great series on historical electronics.  I know many of us have meters and scopes that do it better and easier, but sometimes you need to take a step back and go back to first principles and early gear to really understand how things got to be how they are.

[bxs]

The video quality has definitely gone down these last few videos, it's noticeably worse since you went to 60 fps. Maybe YouTube re-encodes for the 30 fps version.

I have to agree, I don't know about the 60fps videos since I don't watch them, but the "normal" videos are I lot harder to see, when something moves it can be really bad.

If I have to guess I will point the algo used to convert from 60fps to lower fps as the culprit.

[LaurenceW]

Has anybody done a RISK ASSESSMENT on Dave's choice of letter opener? I was going to send him an economy pack of Elastoplast, but now I'm worried he'd cut himself opening the package...

[Lightages]

I have to agree with the video quality this time. I watch using Firefox and it looked more like 480P than 1080P.

[rsjsouza]

I have to agree with the video quality this time. I watch using Firefox and it looked more like 480P than 1080P.

I started watching it on FireFox and it was autoset to 240. When I jacked it up to 360 the quality improved a lot for a mailbag segment (I don't need much detail to look at packages or maybe my standards are too low, I don't know). After reading your comment I jacked up to 1080p and I could see the quality did not improve by a huge margin - therefore yeah, the quality of the full sized video is not really very good.

OT: Lightages, the youtube linked in your signature is pointing to a private video.

 

[Lightages]

Thanks, will fix

[tombi]

I'd love a video showcasing some of the ancient stuff Dave has been sent, like that watt meter, in action if possible.  Going in to why these instruments existed, what they do and why you'd use one (back in the day).  Would make a great series on historical electronics.  I know many of us have meters and scopes that do it better and easier, but sometimes you need to take a step back and go back to first principles and early gear to really understand how things got to be how they are.

Dave must have a heap of old equipment like this from mailbag. I wonder if the guys at the Powerhouse Museum would want to collaborate on a video like this. I bet they have even more!

[JackOfVA]

The Weston wattmeter movement, I believe, is a more or less standard for the era and consists of a fixed winding (potential) and a rotating winding (current).  A couple years ago, I disassembled a 1930's manufactured electrodynamic wattmeter, some photos below. It used a transformer instead of series resistance to limit current in the potential winding. The net torque on the pointer in these instruments is thus proportional to the product of the potential and current coil magnetic fields, i.e., true power.

Note the heavy damping on the moving pointer via the aluminum "paddle" - since the instrument is rated from DC to 120 Hz (the one I took apart), and since there was some 25 Hz distribution used in that era (think it's pretty much limited to railroad use now, but some large factory motors used 25 Hz in that era), heavy damping is needed to stabilize the pointer at the lower end of the frequency range.

[Fungus]

Re. the proportional joystick movement: Are you sure there's no Hall effect sensors in there? Those fixed output points (the ones with with wipers) could be for calibration of the Hall effect sensors.

Could also use carbon track resistor elements directly on the pcb?

Sure.... It just seems weird

OK, saw the video and Hall effect is an optional extra. It all makes sense now... 

[Len]

Has anybody done a RISK ASSESSMENT on Dave's choice of letter opener? I was going to send him an economy pack of Elastoplast, but now I'm worried he'd cut himself opening the package...

Don't worry, the only thing Dave has cut himself on lately is an oscilloscope. 

http://youtu.be/H9QONLaitWU?t=2m4s

[HeywoodFloyd]

The watt-meter, does it still work? I'd love to see if it works and if it's still accurate. Looks like a good build (apart from that loose bit) and maybe the components just never die...

And thanks for the link to Talking Electronics. As an electronics hobbyist I find those sort of microprojects are a great place to start experimenting.

[errsu]

While living in Germany, never heared about Hazet. Asked today in my favorite tool shop: Hazet seems to be one of the - if not the one - most expensive and best quality toolmakers here.

For the screwdrivers - did you note the small yellow cap? You can use it instead of the large handle to get a precision screwdriver, which you can use like those used for clock repair etc., i.e. hold with the index finger and turn with thumb and middle finger.

/errsu

[Neganur]

Aye, Hazet, Gedore, you know those names when you fix stuff on you own (motorcycle, or car) or have friends who do. They're nice tools.

[sdscotto]

I followed the link provided to buy some of the "Iconic: A Photographic Tribute to Apple Innovation" books. 

If you liked and wanted the packaging that Dave displayed in the video, you'll be disappointed to know that is not what you'll get.  It's a hard cover book wrapped in plastic.  :-(

Any idea how to get one with the fancy packaging?

[Gromitt]

I followed the link provided to buy some of the "Iconic: A Photographic Tribute to Apple Innovation" books. 

If you liked and wanted the packaging that Dave displayed in the video, you'll be disappointed to know that is not what you'll get.  It's a hard cover book wrapped in plastic.  :-(

Any idea how to get one with the fancy packaging?

http://iconicbook.myshopify.com/collections/full-collection/products/ultimate

Costs 250 USD, free postage anywhere  , but the box costs much more than the book  .

/stefan

[bigsky]

While living in Germany, never heared about Hazet. Asked today in my favorite tool shop: Hazet seems to be one of the - if not the one - most expensive and best quality toolmakers here.

Absolutely. Hazet don't have a high profile but they are extremely highly regarded by those in the know. You'll see lots of praise for them on Garage Journal - I guess their main following is in the mechanics community.

Dave mentioned he'd never seen interchangeable insulated screwdrivers before. Both Wera and Wiha also make them. These are german firms again - Wera specialises in screwdrives but also does socket wrenches, Wiha does mostly screwdrivers and pliers. Germany seems to be one of the few western countries that still makes good tools - I'm in the UK and our tool industry has virtually disappeared in the last 20 or so years.

[lightman]

Dave please do (when you can) a teardown of that old russian sinclair clone computer, I will love to see how they did it!.
thanks